ACabbr.1. adult contemporary (radio format)2. or a/c air conditioning3. air-cool4. alternating current5. area codeAc 1The symbol for actinium.Ac 2abbr. Bible Acts of the ApostlesAmerican Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.ac the internet domain name for (Computer Science) Ascension Island Ac the chemical symbol for (Chemistry) actinium AC abbreviation for 1. (Electrical Engineering) alternating current. Compare DC 2. ante Christum 3. (Military) Air Corps 4. (Athletics (Track & Field)) athletic club 5. Companion of the Order of Australia 6. (Brewing) appellation d’origine contrôlée: the highest French wine classification; indicates that the wine meets strict requirements concerning area of production, strength, etc. See VDQS, vin de pays, vin de table 7. (Government, Politics & Diplomacy) Aelodau’r Cynulliad: Member of the Assembly (that is, the National Assembly of Wales) [(for sense 3) Latin: before Christ]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014AC or A.C. 1. air conditioning. 2. Also, ac, a.c., alternating current. 3. before Christ. [